This invention relates to transducer positioning and more particularly to phase modulated servo systems for accessing and following data tracks on a rotating medium.
The accepted method of determining transducer position is through an amplitude measurement of signals from adjoining servo tracks to generate a net signal indicative of the radial displacement from a predetermined track centerline. As track densities have increased, the capability of this technique has been enlarged by progressing from dibit to tribit to pentabit servo formats to increase the number of tracks in the capture area and enable more precise track identification. Any of these techniques has been susceptible to inaccuracy as a result of random electrical noise occurring during the servo signal window, and to mitigate this disability, the servo format has often used redundant signals which are averaged to obtain a more uniform approximation to the true value.